Role of Single and Dual-Cavity Structures Inside Evaporator on the Enhancement of Thermal Performance of Pulsating Heat Pipes

Through careful experimentation, this paper focuses on the augmentation of the heat transfer coefficient by impregnating single and dual-feature cavity structures at the floor of the evaporator surface inside the multiloop pulsating heat pipe (MLPHP). Explanations of observed thermal behavior in the augmented loop are presented through the fluidic observations like the ability to produce bubbles due to phase change, ease in heat transport to the condenser through slug plug, and better replenishment path for condensed liquid to the evaporator. Results revealed that a dual-cavity performs better than a single-cavity inside the evaporator of the MLPHP. An array of isolated dimple cavity features performs better than the continuous tunnel and rectangular slot features in the single-cavity category inside the evaporator section. The most efficient structured surface with dual-features, i.e., tunnel-dimple combination inside the evaporator section. The thermal resistances of dimple single-feature cavity and tunnel-dimple dual-feature cavity evaporators are 45% and 73% lower than that of a smooth surface evaporator loop.